Hallowe'en Party is a work of detective fiction by British writer Agatha Christie. It was first published in the UK by the Collins Crime Club in November 1969 and in the US by Dodd, Mead and Company later in the same year.

The story focuses on the death of a young girl at a Hallowe'en party. Joyce, a hostile thirteen-year-old, boasts that she once witnessed a murder. When no-one believes her, she storms off home. But within hours her body is found, still in the house, drowned in an apple-bobbing tub. That night, Hercule Poirot is called in to find the 'evil presence'.

The novel features her Belgian detective Hercule Poirot and the mystery novelist Ariadne Oliver. The novel focuses on child murder (with its possible sexual motivation), the irresponsibility of teenagers and the crisis in crime and punishment.